OSSINING - Ossining High School was briefly locked down this morning for a police investigation.

The school at 29 S. Highland Ave. was locked down because of "an isolated message on social media," the Ossining school district said in an email to parents.

Ossining police tweeted at 9:02 a.m. that the school was locked down and officers were on the scene. At 9:13 a.m. they tweeted that the lockdown was over, but that students would be temporarily kept in classrooms while police finished their investigation.

Police said at 9:25 a.m. that they had cleared the school and classes had resumed. No other information was immediately available.

Claremont Elementary School decided to "shelter in place" and have students go directly to their classrooms upon arriving this morning because of the situation at Ossining High School, the school said in an email. Claremont said it resumed normal activity at 9:08 a.m.